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Harman Kardon Citation 17 troubleshooting

S

streetwise

Active Member
Hello all, Im trying to figure out my Citation 17 preamp, I had everything recapped and resistors replaced to 1% metal film around 10 years ago. the power supply has 16v on the 15v rails right now. does anybody know what resistor to modify to get this into spec? also one of my EQ boards is only putting out static is there any known failure parts on these?

Also the power supply I have is the version with 4 ICs vs 2 as i have noticed there are to different schematics on the web. My board doesn't have the second pilot lamp resistor installed and is also missing a location for R18 a transistor and a cap. Looking on the web I don't see any other schematics or boards that look quite like mine?
 
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streetwise said:
Hello all, Im trying to figure out my Citation 17 preamp, I had everything recapped and resistors replaced to 1% metal film around 10 years ago. the power supply has 16v on the 15v rails right now. does anybody know what resistor to modify to get this into spec? also one of my EQ boards is only putting out static is there any known failure parts on these?

Also the power supply I have is the version with 4 ICs vs 2 as i have noticed there are to different schematics on the web. My board doesn't have the second pilot lamp resistor installed and is also missing a location for R18 a transistor and a cap. Looking on the web I don't see any other schematics or boards that look quite like mine?
Click to expand...
Don't worry about the 1V difference....

Static? Yeah, you have to replace all the transistors as they'll keep getting noisy.

If you have the 356's in your unit, I would socket and replace them:

LF356N/NOPB | DigiKey Electronics

Order today, ships today. LF356N/NOPB – J-FET Amplifier 1 Circuit 8-PDIP from Texas Instruments. Pricing and Availability on millions of electronic components from Digi-Key Electronics.
www.digikey.com www.digikey.com
 
ivandezande said:
Don't worry about the 1V difference....

Static? Yeah, you have to replace all the transistors as they'll keep getting noisy.

If you have the 356's in your unit, I would socket and replace them:

LF356N/NOPB | DigiKey Electronics

Order today, ships today. LF356N/NOPB – J-FET Amplifier 1 Circuit 8-PDIP from Texas Instruments. Pricing and Availability on millions of electronic components from Digi-Key Electronics.
www.digikey.com www.digikey.com
Click to expand...
Ok, just curious what is the safe range of voltage?

I have the older CA3100 opamps, is there a modern replacement for these?

Thanks
 
I used OPA604 as I had scavenged ones from other equipment.

You have to check the pcb wiring to the offset potentiometers if you want to use them, depending on how these are connected to the opams versus the CA3100. Some opamps have the offset pot connected to the negative supply and others to the positive.....

I do not remember if I modified the offset potentiometer wiring or not, as this was long ago.


You can alter the 15 Volts by adjusting the four 18k resistors in the supply to a little lower or parallelling a high value resistor to them, if you are a purist and really want this 16 Volts to be 15 (maybe try 270k or something).

http://www.gerardslikker.nl/hkcitation17.htm Some info here

As @ivandezande states, better replace all transistors, this is easier than trying to find one offender (or multiple of them). Be picky on leg orientation as when you take off all transistors at the same time, it is very easy to make mistakes (been there.....)
 
Luckily I found the issue, the opamps were all fine. I had the same issue after a recap of another preamp. The flux in the solder wasn't cleaned off the board. These boards have very close traces in a few spots and this causes some conductivity. after cleaning up the flux the static has completely gone. The one channel was nothing but static at zero volume before.

I won't bother with the 16v as I rarely use the hi/subsonic cut board or eq's and that is all it drives, and the folks here tell me it won't harm anything being 1 volt off.

any thoughts on adjusting the phono board trimmers? They go from 0-580ohms on mine I have them set around 295ohm as close to center as possible and I don't have a distortion meter or oscilloscope.
 
I am afraid I do not really understand the impact of the pot following the schematic.
I am also not understanding why there is 0.9 Volts over the R5 and R29 resistors in the schematic, while over R24 and R48 there apparently is only 0.1 Volts......according the schematic.
 
gslikker said:
I am afraid I do not really understand the impact of the pot following the schematic.
Click to expand...
Does it maybe provide a minor level of bias 'adjustment' by varying the forward current thru' CR2/3/4 ? sufficient perhaps to allow fine tuning THD ?
I agree with your comment on the numbers - I'm not following them either.
 
another question about the phono schematic the only variation between the two schematics is R15,R16,R39 & R40 are changed from 100 to 39ohm.. but why?

also want to know this about the Output board, the only different values are R16,R17,R35,R36 change from 18 to 47ohm.
R18 & R 37 change from 68 to 82 ohm and are brought up to a 1/2watt resistor
 
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